This project will study methods of varying the strength of social attachment behavior in kittens and the maintenance of the attachment through adulthood. The variables proposed for study have special usefulness for subsequent investigations of the effect of social attachments on aggressive behavior. The experiments will compare the strength of attachment behavior as a function of (a) interspecific vs. conspecific cohabitation, (b) temporal parameters of presentation of a conspecific attachment stimulus, and (c) type of social interaction permitted among conspecific pairs.